Train control



6 Sheets-Sheet H mm- W. K. HOWE TRAIN CONTROL.

Filed Aug. 25, 1924 June 11, 1929.

fl\\\ \L RNEY Julie 11, 1929. w, HOWE 1.717.339

, TRAIN CONTROL Filed Aug. 25, 1924 6 Sheets-Sheet 2 June 11, 1929 w. K.HOWE 1.717.339

TRAIN CONTROL Filed Aug. 25, 1924 6 Sheets-Sheet 3 IN V TOR.

m9 BY FIG. 6.

June 11, 1929.

Filed Aug. 25, 1924 W. K. HOWE TRAIN cou'rRo 6 Sheets$heet INV TOR.

A TT RNEY Patented June 11, 1929.

UNITED/STATES 1 1,717,339 PATENT oF Ics.

WINTHROP K. HOWE, OF ROCHESTER, NEW YORK, 'ASSIGNOR, TOGENERAL SIGNALCOMPANY, OF ROCHESTER, NEW YORK.

TRAIN CONTROL.

Application filed August 25, 1924 Serial No. 733,975,

This invention relates to automatic train control systems, and moreparticularly to continuousinductive control systems of the so-calledthree-speed of three-position type.

Briefly stated, a system of this kind includes a three-position orpolyphase alternating current relay on a railway vehicle which has oneof its field windings or phases energized in response to current'fiowing down one rail and back through the other ahead of the train,and has its other field winding or phase energized in response tocurrent flowing in the two rails in multiple under the train, thesecurrents being detected by suitable influence receiving means in frontof the first axle and at a point some distance in the rear of the firstaxle, respectively, and being amplified by suitable vacuum tubeamplifiers and associateddevices. By reason of the factthat the relay isnormally energized in response to trackway current, it is difficult tokeep this relay from droppingwhen certain sections are passed where itis difiicult to provide such current in the track rails. These sectionsare conveniently called dead-sectionsv, and are found at frogs,cross-overs, staggered joints between blocks, and the like. v

In the provision of automatic train control apparatus, it is desirableto maintain the protection that is afforded without suchapparatus,namely, that due to the vigilance of the engineer; and in order tomaintain such vigilance and keep the engineer from wholly relying on theautomatic apparatus, it is proposed in accordance with the presentinvention to require him to perform a certain act in passing orapproaching a caution, or. a danger signal, to show, that he hasobserved the signal and knows that he is entering more dangerousterritory. Such an acknowledging act is conveniently enforced byrequiring theengineer to operate some thing, such as a push button, ator just before the time when the relay changes either from a clear or acaution to a more dangerous position.

Since, as heretofore,mentioned, dead-sections are bound to beencountered, it is proposed" in accordance with the present invention torequire the engineer to manifest his viligance onlywvhen the relaychanges to an adverse position and stays there for a certaindistance ofmovement of the. train. It is considered that such acknowledging actmanifests that the engineeris alive and alert,

danger ed SPGQClllll'lltS. Further, in order to give the engineeradequate'information as to what'he is required to do in order to avoidan automatic brake'application and an associated penalty it is proposedin accordance with the presentinvention 'to providea suitable warningsignal, which will keep him sufficiently informed to enable him tocontrol the train without the infliction of such a penalty. Theparticular type of audible warningrsignal proposed in connection withthe present invention is one telling the-engineer when he hassufliciently decreased his speed, rather than telling him when his speedis excessive.

Since automatic train control systems of the continuous inductive typeare of a character that restrict the speed uponabsence of trackwaycurrent, it is essential to provide suitable'means for maintaining thecar-carried train control mechanism in an inactive or non-controllingcondition when the train enters territory which is not equipped forautomatic train'control. purposes; and in accordance with the presentinvention, it is proposed to provide a stick relay which, when in, itsenergized position, advises the engineer by a suitable cab signal thathe is moving in non-control territory and which makes a portion or allof the train control mechanisminoperative, this relay preferably beingautomatically picked up in response to a change from the normallyenergized position of the relay to a ole-energizedposition thereof,providing the engineer makes a cer tain acknowledging act at the timetoshow that he is aware of entering such non-control territory.

Other objects, purposes, advantages and characteristic features of theinvention will in part be pointed out hereinafter and in part be obviousfrom the accompanying drawings.

In describing the invention in detail reference will be made to theaccompanying drawings in which Fig. 1 shows a portion of trackwayequipped for train control purposes, together with a conventionalillustration of a railway vehicle equipped with a main car relay andsuitable 'current detecting and amplifying devices, the shaded areasshown in this figure representing the various speeds through varioussections of a caution block at which an audible warning signal issounded;

Fig. 2 shows mechanism for closing contacts at different speeds, atdifferent distances from a certain point at which the main car relay haschanged, and if the actual speed as compared with a permissive speed isexcessive;

Fig. 3 conventionally illustrates the co-car ried apparatus togetherwith the circuit arrangement connecting the various elements carried onthe car;

Fig. 4: shows the various speeds above which the audible warning signalis sounded through certain sections in a caution block by thecar-carried apparatus shown in Fig. 3, with the warning signal controlmodified as shown in Fig. 4A;

Fig. 4A shows a modified form of control of the warning signal;

Fig. 5 illustrates the various speeds be tween which, as well as thesections through which, the warning signal is sounded when employing themodified form of 1 control shown in Fig. 5A;

Fig. 5A shows a further modified form of control for the warning signal;and

Fig. 6 shows a modified type of trackway system, whereby the trainhasits maximum permissive speed gradually reduced in the first clear blockin the rear of a caution block.

Referring to Fig. 1 ofthe drawings, a track has been illustrated byrails 1 divided into blocks in the usual way by insulated joints 2, theblock I and the adjacent ends of two other blocks H and J being shown.Since the various parts and. circuits associated with the blocks are thesame, like parts of each block are designated by like referencecharacters having distinctive exponents.

At the exit end of each block is impressed across the rails the usualsource of trackway energy,which in the arrangement shown is supplied bya transformer 3 connected across the track through an impedance la Asuitable track relay 5, responsive to alternating current, is connectedacross the rails at the entrance end of such blocks. Although the traincontrol system embodying the present invention may be used either withor without wayside signals, wayside signals are preferably employed toaid the engineer inacknowledging, and although either'light signals orsemaphore signals may is deenergized.

be used for convenience semaphoresignals Z only have been shownconventionally, without illustrating their well known con trol circuitsand devices.

In addition to the usual alternating current normally closed trackcircuit, which receives its energy from the transformer 3, circuits areprovided for causing a flow of current through the two rails inmultiple. This current is displaced in phase with respect to the trackcircuit current, and is at times out off in accordance with trafficconditions ahead; and for conducting this current to the rails thebalancing resistances 6, 7 and 8 have been illustrated, which arelocated at the entrance end, at an intermediate point B, and at the exitend of the block, respectively. The first section of the block,extending from the balancing resistance 6 to the balancing resistance 7,has current applied thereto in one direction or the other, depending onwhether the track relay in the next block in advance is energized orde-energised, through circuits including front contacts 10 and 11 whichcircuits are readily traced in the drawings; and the second section ofthe block extending from balancing resistance 7 to balancing resistance8 has its line phase energized only when the contact 12 of the trackrelay .5 is in'its raised position.

For convenience, the usual track circuit will be referred to as thetrack phase or loop circuit hereinafter, and the circuit including thetwo rails in multiple will be referred to as the line phase or simplexcircuit.

On the railway vehicle, conventionally illustrated by the wheels andaxles 15, is provided a main car or control relay MB of the polyphaseinduction type. This relay is preferably constructed like those commonlyused in railway signalling; and gen erally speaking, it has two fieldwindings and a movable ele1nent, such as a rotor or a vane, togetherwith suitable contact fingers operated by said movable element. Therelay MB is biased by suitable springs or counter-weights so that itsmovable element assumes an intermediate or neutral position if eitherone or both of its field windings The contacts operated by the movableelement MR'have been shown conventionally as single contact fingers,capable of assuming any one of three dilii'erent positions and arrangedto cooperate with stationary contacts indicated as arrows.

Directly ahead of the first axle of the train is carried a pair ofinfluence receiving elements or coils 16, which are connected to thetrack phase amplifying device TA in a manner so that voltages induced inthese coils, due to currents flowing in opposite,

directions in the rails, are cumulative. The

tying device TA are connected to one :field winding 17 of the main relayMR, so that a current is caused to flow inthe coil 17 of this relay inresponse'to current flow in the track phase, that is, in one directionin one rail and in the other direction in the other rail ahead of thetrain. Similarly, another pair of influence receiving coils or elements18 is provided several axles in the rear of the first axle, andpreferably in the rear of the tender; and these coils are connected inseries to the line phase amplifying device LA in a manner so that thevoltages induced in these coils, due to currents flowing in the samedirection in the track rails, are cumulative, the output leads of thisamplifying device LA being connected to the other coil 19 of the mainrelay MR. In the arrange 'ment shown these coils 16 and 18 surroundcores of laminated iron, which are adapted to act as flux collectors,but these cores may be omitted if desired, from certain systemsdepending on the frequency and value of the trackway currents used.

If the trackway currents flowing in the track and line phaserespectively are displaced in phase the relay MB is energized to shiftits movable element in one direction and if one of these phases isreversed, the relay is'energized to shift its movable element in theother direction; and if either of these phases has its currentinterrupted, the movable element of the relay assumes its deenergizedposition. It is thus noted that a train moving in a clear block willhave this relay energized in the normal position, and as the trainenters a caution block, the relay will assume its reve *sed positionbetween the entrance to the block and the point B, and will assume itsde-energized position from the point B to the end of the block, all byreason of the control effective on the line phase circuit. Also, as thetrain moves in an occupied block, this relay assumes its deenergizedposition, because there is no track phase current present in suchoccupied block, since this currentis shunted from the train in questionby-another train ahead.

As shown in Fig. 1 and as heretofore mentioned, the blocks are dividedinto two sections as far as their control is concerned under cautiontraffic conditions of a block; that is, at the entrance to a cautionblock the main relay changes from its normal onergized position to itsreversedposition, and at the point B in the block it changes the secondsection, respectively, of a caution block, similar to-the arrangementshown in the application filed July 26, 1923-by Howe and Bushnell, No.653,898, to which reference may be had, so that a brief descriptionofuthe car-carried apparatus will sutlice herein.

Referring now to. Fig. 2, there has been shown an arrangement ofmechanisms whereby circuits may be made and broken at different speeds,after the train has moved a certain distance into the first or secondsection of a caution block, and if the actual speed of the train is toohigh as compared with a permissive speed set up by suitable cams,operation of which is initiated near the entrance to such sections. Thereference character 20 represents a shaft driven from one of the axlesshown in Fig. 1 in any suitable manner, on which is contained acentrifugal speed responsive device or centrifuge C. This centrifuge Cmay take any desired form; and in the simple conventional manner inwhich it has been illustrated, comprises a grooved collar 21 which isslidably mounted on the shaft and is adapted to be moved endwise on thisshaftin response to centrifugal. force acting on the fly balls orweights 22 in opposition to the compression spring 23, this springtending to hold the weights near the shaft. Near the centrifuge O, andmounted for rotation in journals 24, is a speed shaft 25 to which iskeyed an arm 26 having its free end bifur-' cated and containinginwardly extending pins straddling the grooved collar 21 with the pinsengaging the groove, so that the shaft 25 assumes a positioncorresponding to the speed of the train as manifested by the position ofthe collar 21 on the shaft 20. To the shaft 25 is pinned a speed cam 29having a pair of contacts 30 associated therewith, the movable contactof which is pro vided with a roller 31 engaging the surface of the cam29. These parts are so related with respect to each other that thecontacts .80 are brought into contacting relationship when the speed asindicated by the centrifugeC is below 20 miles per hour.v

As heretofore mentioned, the present system of train control includestwo separate speed-distance cams adapted to be driven from the wheels ofthe railway vehicle through different, sections depending on thecharacter of the tra'ckway current in such sections. Two such camcontrolling mechanisms have been illustrated in Fig. 2, and

since these are essentially the same, except as to the shapes of thevarious camsemployed, the description of one of these mecha nisms willsuffice for both, and like parts of the other mechanism will beindentified by the same reference characters having distinctiveexponents.

Referring to Fig.2, to the shaft 20 driven from the car wheels is pinneda Worm 33, which meshes with a worm wheel 34 pinned to al shaft 35,supported for rotation in journals 36.- On this shaft 85 is ikeyed apinion 37 meshing with a gear 38 which is supported for rotation on apin 39. This pin 39 also forms a bearing support for the bifurcated endof an arm 40 of a cam starter mechanism HOS used to control the high tomedium cam HG. In the bifurcated portion of this arm 40 is pivotallysupported a pinion 41, which is in continuous meshed re lation with thegear 38. The free end of this arm 40 is spring-pressed upwardly by acompression spring 42, guided by a .rod 43 fastened in a stationary lug44. Under normal clear traffic conditions, the arm 40 is held in itslower position as shown by the cam starter magnet HUS which is thenenergized and attracts the armature 45 fastened to this arm 40. Directlyover the. pinion 41 is a distance cam shaft 47, supported in journals48, and having a multilatcd gear 49, a pinion 50, the cam HQ, and adistance cam 51 pinned thereto. The multilated gear 49 has a portionthereof cut away, so that when the cam starter magnet HCS is deenergizedand the spring 42 moves the pinion 41 into engagement with thismutilated gear, this mutilated gear 49 may be turned only through anangle of substantially 180, after which no further turning takes placeby reason of this mutilated portion.

The shaft 47 is held in its normal position as shown by a suitablespring returning mechanism, which in the particular arrange ment shown,comprises a sector 53 pivotally supported on a pin 54 and held in itsnormal position by the opposing springs 55 between the lugs 56 and thearm of the sector 53. This sector 53 meshes with the pinion 50 on shaft47 and holds the shaft 47 in the normal position with themutilated'portion of the gear 49 rotated 180 degrees from the pinion 41.

The cam 51 heretofore mentioned may be convenientlycalled a distancecam, because it is adapted to make and break circuits depending on thedistance the train has moved after the cam starter magnet HCS has beende-energized. As shown, this distance cam 51 maintains the contacts 58closed so long as the roller 59 is 011 either of the elevated portionsof this cam 51.

In order to operate a contact when the speed, as indicated by thecentrifuge C, is

too high as compared with the permissive speed set up by thehigh-to-medium speeddistance cam HG, a floating lever mechanism isemployed, which includes a speed arm 60 having its free end pivotallyconnected to the lower end of a floating lever 61. The upper end of thelever 61 has a roller 62 engaging the edge or cam surface of the cam HG.I It is thus noted that any intermediate point on this floating lever 61responds both to the speed of the train as well as the position of thecam HO, and all that is necessary, in order to control a circuit whenthe actual Speed is too high as compared with the permissive speed setup by the cam HC, is to operate a switch in response to the position ofsuch intermediate point. In the arrangement shown, this mechanismcomprises a sector 63 pivotallysupported on a pin 64 having a pin 65eccentrically located therein, to which is pivotally secured a link 67having its other end connected at an intermediate point by a pin 66 tothe floating lever 61. This sector 63 is urged in a counter-clockwisedirection by a spring 68 and in turn urges the roller 62 against the camH0. The sector 63 is so shaped that, when turned in a clockwisedirection through a certain degree or angle, the contacts 110 open.

Fig. 3 of the drawings shows a circuit ar *angement of the car-carriedapparatus, including the mechanism of Fig. 2 and certain other devicesin their normal clear traffic conditions with the train running at aspeed somewhere between the medum and maximum speed adapted to be setup, which apparatus will now be briefly described.

For reasons more clearly pointed out hereinafter, it is desirable toprovide an acknowledging device which the engineer may operate to showhis alertness; and, on account of the fact that such an acknowledgingact should not be required until after the train has run a certaindistance in more restrictive territory, in order to obviate necessityfor acknowledgment on account of dead-sections, this acknowledgingdevice is preferably so constructed that it need only be momentarilyoperated. In the arrangement shown, a plunger 70, having a return spring71 and contacts 72 and 7 3, is provided with an armature 74, which canbe held down in opposition to the spring 71 by energization of either ofthe windings 75 and 76.

One of the essential elements of any train control. system is a suitablemeans for effecting a brake application by the usual air brake mechanismunder certain predetermined conditions. Since the present inventionrelates more particularly to means for actuating said brake applyingmechanism and does not relate to the mechanism itself, no particularform of brake control device has been shown. It contemplated that suchbrake applying device be operated pneumatically; and anelectro-pneumatic device EPV which is electrically controlled has beenshown for this purpose.

As heretofore mentioned, it is desirable to give the engineer adequate.information so that he may control the train without having a penaltyinflicted upon'him if he is vigilant and alert" in attending to hisduties, and for this purpose four distinctive types of cab signalshavebeen provided. These signals may first be divided as visual signals,or audible signals. The visual signals Y, NOS, B; and G have been shownby the 7 preferably used to indicate a change to, orv

circles and preferably comprise suitable incandesccntlamps or lightsignals. The audible signals have been shown bysquares and are of threedifferent types. The first type,

type of audible signal is one that is momen tarily sounded when it isbeing energized and 18 again momentarilysounded when it is beingde-energized. This third type is from, clear, caution and danger,respectively; and a signal of this type is connected in multiple withthe green, yellow and red lamps G, Y and R. The single and double strokeaudible signals just mentioned preferably consist of the usual type ofsingle stroke electrical gong. If the gong is to be sounded only when itis energized, it is placed on the tractive side of the armature;

if it is to be sounded when it is de-energized,

the gong is placed onthe retractive side of the armature; and 1f 1t isto be sounded both when it is energized and when 1t 1s de-energized, twogongs are used placed one on each side of the armature.

Operation.

In reviewing the operation of the car-carried mechanism shown in Fig.3no particular reference will be made to the trackway a1i )pai'atus, itbeing understood that a change from normal phase relation to reversephase relation of trackway current encountered by a moving train causesthe main relay MB to assume the reverse position, and that the presenceoi one kind of current only, or no current, on the trackway causes thisrelay to assumcits tie-energized position.

The circuits interconnecting and controlling the various parts of thecar equipment are shown in Fig; 3 in a simplified and dia-.

grammatic manner. The'source of energy is illustrated a battery 100,which may, however, be a turbo-generator or other suitable source ofelectrical current. 80 at the left hand side of Fig. 3 is connected toone terminal of the battery 100, assumed to be the positive terminal,and is called the positive bus. The other wire 90 at the right hand sideof Fig. 3 is connected to the negative terminal. Thevarious speedcontacts areshown one above the other and are connected by adot-and-dash line representing the speed shaft 25 2) The speeds at whichthe several speed contacts open or close are'indicated by figures. Thevarious distance contacts, controlled by the cam starter magnet HCS, areillustrated as oper- The wire ated by cam members connected by adotand-dash line representing the shaft 47. Similarly, the distancecontacts operated by the cam starter magnet LCS are shown connected by adot-'and-dash line. The several cont-act fingers or armatures operatedby the relays A070, PR and N C, are shown below the conventionalrepresentation of the relay winding and are connected by dash lines,

In order to understand the circuit arrangement in Fig. 3, it isconsidered expedient to traceall of the important closed circuits first,after which changes in these circuits and devices may be readilyconsidered and understood.

, The control circuit for the normally energized penalty relay PR may betraced as follows :-beginning at the positive bus 80, wire 81, distancecontacts 82, wire 77, distance contacts 83, wires 84 and 85, front contact 86 of penalty relay PR, wires 87 and 88, winding of the penaltyrelay PR, wire 89 to the negative bus 90. There is still another circuitfor energizing this relay PR, namely, the circuit including the contact13 of the relay MR, and the purpose for this latter circuit and theparts included therein, arepointed out more particularly hereinafter. I

The circuit forenergizing the cam starter magnet HCS may be traced asfollows beginning at the bus 80, wire 91, contact 92 of the main controlrelay MR, wires 93 and 94, Winding of the cam starter magnet HCS, wire95, back contact 97 of the acknowledging relay A076, wire 98, back tothe negative bus 90 of the battery 100.

The circuit for the :u'iedium-to-low cam starter magnet LCS may betraced as follows :beginning at the bus 80, wire 101, contact 102 of themain relay MR, wires 103 and 104, winding of the low cam starter magnetLCS, wire 105, back contact 96, wires 106 and 98, t0 the negative bus90. I

A normally closed circuit for the brake control device EPV may be tracedas follows :-beginning at the bus 80, wire 109, cam governor contact110,-wires 111 and 112, distance contacts 113, wires 114, 115 and 116,frontcontact 117 of the penalty relay PR, wires 118 and 119, front orstick contact 120 of the device EPV, wires 121, 122, 123, winding of thedevice EPV, wire 124 to bus 90. It should be noted. that the device EPVis normally made non-stick because stick or front contact 120 is shuntedby a partial circuit including the wires 125, 127 and 129 and thecontacts 58 and 58 Beforetaking up the actual operation of the systemunder different traffic conditions, let us assume that the main relay MRchanges from its normal position as shown to its de-energized position,as would ordinarily occur when a train passes a so-called dead-section.This causes the high tomedium cam starter magnet HGS and also themedium-to-low cam starter magnet LGS to be de-energized, therebyinitiating both of these cams. Let us assume that a distance of, say 200feet, will be the longest dead-section encountered in practice. The camHG is preferably so shaped that the permissive speed set up by this camHG is not reduced during this distance of movementl Also, it the mainrelay MB is not de-energizedfor ,a greater distance than 200 feet ofmovement, no acknowledgement is re quired by the engineer, because theenergizing circuit for the penalty relay PR here tofore traced andincluding contacts 82 and 83 is not broken until the train has traveledfor a greater distance than 200 feet under the assumed condition. If thetrain were to travel more than this distance under the assumed conditionthe opening of distance contacts 82 or 83 would break the stick circuitfor the relay PR.

In short, the system of this invention is so organized that there is nochange in the speed limits enforced, nor an automatic brake applicationdue to failure to acknowledge, upon de-energization of the main carrelay MR, until after a certain limited distance of travel which isselected so as to be longer than the longest deadsection distanceencountered on the railroad. On account of this distance lag, it is notnecessary to provide currents at all points along the trackway toinfluence both sets of receiving coils on the locomotive, therebyavoiding the need for wires near the track rails to maintainenergization of the car relay at crossings, the frogs of switches, andstaggered 1o1nts.

Mam'mam speed Zimit.-A continuing maximum speed limit, assumed to be 60miles per hour in this instance, is enforced under clear tratlicconditions. Even with the cam HG in the initial maximum speed position,as shown in Figs. 2 and 3, it will'be evident that the running speed ofthe train cannot exceed a predetermined amount, corresponding to theminimum radius of the cam, without moving the floating lever 61 farenough to open the contacts 110 and apply the brakes. Since the contacts58 and 58 are closed, the cams HG and LG being in the initial position,the valve EPV is connected non-stick; and as soon as the running speedof the train is reduced below the maximum speed limit, the yalve EPV isautomatically re-energized, and the engineer may release the brakes andproceed. The engineer is aided in running at the highest speedconsistent with safety without an automatic brake application by awarning signal as hereinafter explained.

E uteri 1m caution bZ0ck.-Let us now assume that, by reason of enteringa caution block, the main relay MR is changed from its normal position,as shown, to its reverse dotted positlon. Thus change of the relay MRde-energizes the cam starter magnet HGS and causes the high-to-mediumcam HG to be geared to the wheels of the vehicle and gradually rotatedabout its axis and for the same reason gradually rotatesthe distancecams 51, 130, 131 and 132. As this high-t0- medium distance shaft 47 isrotated, the contacts 133 are closed and remain closed for a distanceof, say 300 feet. As soon as contacts 133 close, depression of the pushbutton will cause it to be held down in its depressed position by reasonof the energization ofwinding 7 6 through the circuit readily traced inthe drawings through the contacts 133. This winding 76 is so designedthat it is capable of holding the armature 7 1 down, if it is depressed,but is not able to pull the armature into its depressed position. Byreason of this construction the engineer need not hold down the plungeror push button 70.

With this acknowledging plunger 70 held down as, just explained, acircuit for the acknowledging relay A020- is completed through thecontacts 72, which can be readily traced in the drawings. With thisacknowledging relay A07: energized, an auxiliary stick circuit for thepenalty relay PR is completed and may be traced as follows beginning atthe positive bus 80, wire 135,

front contact 136 of the acknowledging relay Ack, wires 137 and 85,front contact 86 of the penalty relay PR, wires 87 and 88, winding ofthis relay PR and wire 89 back to the negative bus 90 of the battery100.

When the train has traveled a distance of about 250 feet, the contacts83 operated by the distance cam 131 are opened for a short distance oftravel only. Since, however, as just explained, an auxiliary circuit hasbeen completed for the penalty relay PR, this relay is not de-energizedby opening of the contacts 82. A short distance after the contacts 83temporarily open, the contacts 133 open and de-energize the winding 76,permitting the plunger 70 to be returned to its upper position by thespring 71. This opens the contacts 7 2 and causes de-energization of theacknowledging relay A070; but since the contacts 83 are now closed, thepenalty relay PR is maintained energized by its normal stick circuit.

' If the engineer has been asleep, is dead or has not takenvcare of hisduties for some other reason, as would be evidenced by his failure tooperate the acknowledging button, this penalty relay PR would bede-energized upon opening of the contacts 83. Such deenergization of thestick penalty relay PR causes an immediate brake application, becausethe main circuit for the device EPV includes a front contact of thisrelay PR.

Also, since the penalty relay PR is a stick relay, if once de-energized,it remains in its de-energized position until the train has been broughtto a stop or substantially zero miles per hour, whereupon a pick upcircuit for the penalty relay PR is completed which may be traced asfollows :beginning at the positive bus 80, wire 139, contacts 140 and143, wires 144 and 88, winding of the penalty relay PR, wire 89, to thenegative bus 90.

As the train travels through a caution block, assuming acknowledgementon the part of the engineer, the high cam HO turns and imposes agradually reducing speed limit indicated by the curve a in Fig. 1. Ifthe train in time exceeds this speed limit, the contacts 110 open andde-energize the electro-pneumatic valve EPV. Since the contacts 58 arenow open, the shunt around the front contact 120 of the valve EPV isbroken, so that whenever the valve EPV is tie-energized by excessivespeed under caution traffic conditions, it cannot again be re-energizeduntil the contacts 58 re-close except for the contacts 1l014:1 describedhereinafter. Hence, if the engineer does not control his trainproperlyand exceeds the permissive speed limits set up by the cam HG,the brakes are applied and cannot be released until the speed of thetrain has been brought down below the intermediate or medium speed.

After the train has traveled part way through the caution block, the camshaft HC is turned to a point where the pinion t1 rotates idly in themutilated portion of the gear 49, holding the cam in this intermediateor sub-maximum speed position. The train may continue at any speed lessthan this medium speed, assumed to be tO milesper hour, until the pointB, at which the balancing resistance 7 is located, is reached. If thetrain exceeds this medium speed limit, the brakes are automaticallyapplied, but can be released as soon as the speed has been reduced belowthis limit,'since the contacts 58 are closed.

As the train passes the point B in the caution block, the fingers of themain car relay assume the middle or neutral position, the finger 102breaking the energizing circuit for the cam starter magnet LCS. The camLC is now connected to the wheels of the vehicle, and after the trainruns for a short distance longer than the dead-section distance, thecontacts 113 open, breaking a shunt including wires 112, 114 and 115around the contacts 110, so that these contacts 110 of the cam LC are incontrol of the valve EPV and will act to de-energize this valve if thetrain exceeds the permissive speed limits set up by this cam. Contacts58 open soon as the shaft of the cam LC starts and makes the valve EPVstick. Consequently, if the train exceeds at any point the permissivespeed limit set up by the cam LC, indicated by the curve?) in Fig. 1,the brakes cannot be released until the train has been brought to astop, at-which contacts 140-141 close, or until the contacts 58 arere-closed. Before the train reaches the end of the block, the cam LCreaches'its minimum speed position, the pinion 41 1o tating idly in themutilated portion of the gear 49 After the train has advanced beyond thepoint B in a caution block to a point selected to be braking distancefor the minimum speed from the eXit end of the block, the contacts 1416close, establishing a circuit for the acknowledging signal Aclc. S,running from positive wire 80, contacts 146, contact finger 73 and frontcontact of the acknowledging device 70, signal A072. S to negative wire90, and also energizing the upper winding 75 through a circuit obviousfrom the drawing. Upon giving of this acknowledging signal, the engineeris supposed to operate the acknowledging contactor 70, opening thecontacts 7 3 to stop the signal and closing contacts 72 to energize theacknowledging relay A070. The energized winding 75 holds the plunger 70of the acknowledging c011- tactor in its lower position in the same waypreviously described, until the contacts 14-6 open. After a shortdistance of further travel, sufficient to afford the engineeropportunity to manipulate his acknowledging contactor and energize theacknowledging relay A070, the contacts 82 open and make a break v 'inthe normal stick circuit for the penalty relay PR. Since theacknowledging relay A070 is energized, proper acknowledgment beingassumed, the penalty relay PR is held up by its auxiliary stick circuit,and no brake application occurs. It will be evident'that, if theengineer failed to acknowledge, the penalty relay PR would bede-energized,

applying the brakes and maintaining them applied until the train hadbeen brought substantially to a stop and the contacts 14() 143 closed.1',

It will be noted. that the acknowledging signal A070. S is automaticallygiven before acknowledgment is required of the engineer near the end ofthe caution block, in recognition of the danger or stop signal, and thatthis acknowledging signal is given after passing the caution signal.This arrangement is adopted on the theory that the en gineer'can tellfrom the caution indication and location of the block signal when tomake his cautionary acknowledgement. The acknowledging point for thestop signal, however, will in practice be somewhat variable, due towheel wear, diiferences in a grade, or the like; and while a suitablemarker along the track (not shown) might be used to indicate the pointof acknowledgment, it is preferred to operate the acknowledging signal,which will always be a short ill interval of distance in advance of theactual point of acknowledgment and will atl'ord the engineer reasonableopportunity to act in every case.

In connection with the acknowledgment required of the engineer, itshould be noted that no acknowledgment is required at a caution signalwhen the speed is less than 20 miles per hour, since the speed contacts7 8, closed below 20 miles per hour, shunt the contacts 83.Acknowledgment for each stop signal is required irrespective of thespeed, since opening of the contacts 82, with the main car relay MRde-energized, breaks the normal stick circuit for the penalty relay PRand would result in de-energization of this relay and a brakeapplication, unless the acknowledging relay A070 were energized.

If the engineer should attempt to defeat the purpose of the system andavoid acknowledgment by tying or fastening down the acknowledgingcontactor 70, the resultant energization of the acknowledging relay Ada,by opening back contacts 97 and 96 of said relay, would tie-energizeboth of the cam starter magnets HCS and LCS, resulting ultimately in theenforcement of a minimum speed, which would serve to deter the engineerfrom attempting to avoid acknowledgment in this way.

If the block in advance should become unoccupied at any time while thetrain is travelling in a caution block, the contact lingers of the maincar relay MR would assume the normal position shown in Fig. 3, thereby Venergizing both of the cam starter magnets and returning the cams to thenormal initial position; there is a momentary opening of thecontacts 82and 83, and to avoid de-energization ot the. penalty relay PR under suchconditions, this relay is held up by a circuit through the normalcontact of the finger 13 of the main car relay MR, as already indicated.

Entering a danger bc7c.As the train passes from a caution to a dangerblock, there is no change in the car equipment. The main car relayremains tie-energized and the cams HC and LC in their run downpositions; A minimum speed limit is maintained throughout the dangerblock.

It a danger block changes to a caution block, while the train is to therear of the point B, the contact fingers of the relay MR assume thereverse position, returning the cam LG to the normal position, but notthe cam HG. During this return movement of the cam LC, the contacts 82are shunted by the reverse contact of the finger 13 of the relay MR. Ifthe train should be in advance of the point B, when the block changesfrom danger to caution, no change in the car equipment takes place, thecar relay MR remaining tie-energized.

Open switch and broken mil pr0te0te'0n. In the continuous inductivecontrol type of system, the relay MB on a train is at all timesresponsive, not only to the track circuit oi the block next in advance,but to the presence of a train in the same block, the conditions of theswitches, and the integrity of the track rails. If a switch should beopened in advance of a train in the same block, or a. rail break, oranother train back into that block, the car relay MR would bede-energized and the lou speed cam LO immediately started, bringing thespeed of the train down to a minimum speed. It the train is travellingat a high speed at the time of such sudden danger condition, an immedi'ate brake application occurs, because as soon as the cam LC starts, themedium speed limit is effective.

Gab signaZs.Under normally clear trailic 7 conditions of the apparatusas shown, a green cab signal G indicating clear traiiic conditions isdisplayed, being energized through a circuit from the negative wire 90,signal G, contact tinger165 and back contact of relay NC, contact linger92 and normal contact of relay MB, to positive wire and with this visualsignal there is also associated a two stroke audible signal 9, thisaudible signal sounding both when the lamp G is being lighted andextinguished but does not sound while this lamp is illuminated. As themain relay l IR changes from its normal to its reverse position, theclear lamp G is extinguished with a single tap' of a bell or the like,and the yellow lamp Y is illuminated through a circuit including wire90, signal Y, finger 92 in reverse position, and wire 80, with a similartap by the audible signal 3/. Similarly, the change from the reverse tothe ale-energized position of the main relay MR causes the yellow lampto be extin guished, sounds the audible signal y with a single tap andcauses the danger signal R to be displayed through a circuit including,wire 90, signal It, finger 159 and back contact of relay NC, wire 158,finger 157 of MB in tie-energized position, and wires 156 and 80, andalso sounds the audible signal 9* with a single tap, so that threedistinct audible signals are given when the traiiic conditions change asevidenced by the main relay MR.

Non-control term'tory.-As heretofore mentioned, when a train runs intoterritory which is not equipped for train control purposes, no trackwaycurrent is available, certainly not in two different circuits which havea phase relation so as to cause response of the main relay MR on thetrain; and without provision to the contrary, the train would berequired to travel at its minimum speed with the low cam in its ultimateposition In order to permit movement of the train at a higher speed, andalso to advise the engineer that he is running in non-traincontrolterritory, a non-train control relay NC is provided. This relay NC isconnected in circuits with contacts operated by the main relay MR sothat when the main relay changes from clear to danger, that is, from thenormal energized position to the deenergized position, itbeingunderstood that at the entrance to non-train control territory thetracks are constantly furnished with line and track phase currents toprovide clear track conditions for a short distance, this relay NC maybe picked up and stuck up, providing the engineer operates theacknowledging push button 70.

Let us assume that a train is running in clear territory but is justabout to enter territory not equipped for train control purposes. As theengineer operates the push button 70, a pick-up circuit for the relay NCis completed as follows F-beginning at the positive bus 80, wire 91,contact 92 of the main relay MR, wires 93, 150 and 151, front contact152 of the acknowledging relay A070,

wires 153 and 15 1-, winding of the relay NC,

wire 155 to the negative bus 90. It is desired to point out thatoperation of the acknowledging push button upon a changed from clear tocaution traffic condition illuminates the non-control signal lamp NCSdue to energization of the relay NC only in the event that the pushbutton is depressed before the main relay MR has changed from its clearto its caution position. This is, however, not the contemplatedoperation of the system, the engineer not being supposed to operate thepush button 70 until the relay has already assumed the caution position.It the engineer does depress the ush button 70 before the relay MRchanges From clear to caution the relay NC may be picked up andtemporarily stuck up through contact 165, but in this event the caution.lamp Y is illuminated as soon as the main relay MR changes from clear tocaution, thus giving the engineer two conflicting signals which, ofcourse, will indicate to him that he is not operating in non-controlterritory.

.lVith the relay NC energized through its pick-up circuit for reasonsjust given, a change of the main relay MR from its normal to itsde-energized position completes a circuit for this relay which may betraced as follows :beginning at the positive bus 80, wire 156, contact157 of the main relay MR, wire 158, contact 159 of the relay NC, wires160, 161 and 154, winding of the relay NC, wire 155 to the negative bus90.

lVith this relay NC energized by this stick circuit, a circuit forilluminating the non-train control signal NCS is completed which isreadily traced in the drawings. lVhen this visual non-control signal NCSis being energized, no sound of the audible signal associated therewithis given, but such a sound is given when this relay is againdeenergized, this occurring when the train reenters signal territory andcauses the main relay MB to be picked up in either the normal orreversed position thereby breaking the stick circuit for thisnon-control relay NC. It is desired to point out that if a trainre-enters signalled territory after having moved in non-controlterritory, that the non-control signal lamp NCS will not be extinguishedeven though the train is movwith traffic conditions existing ahead ofthe train as it should in train control territory. With the non-controlrelay NC in its energized position the following circuits are completedfor energizing the cam starter magnets HCS and LCS, respeetively:- (l)beginning at the positive'bus 80, wires 101, 163 and 164, front contact165 ofthe relay NC, wires 166, 150 and 94, winding ofthe cam startermagnet I-ICS, wire 95, backcontact 97 of the acknowledging relay A c/s(the engineer having released the push button 70), I

wire 98 to the negative bus 90; and (2) beginning 'atthe positivebus 80,wires 101, 163 and 167, front contact 168 of the relay NC, Wires 169, 101, winding of the cam starter magnet LCS, Wire 105, back contact 96 ofthe relay A070, Wires 106 and 98 to the negative bus 90.

Warning signaZ.-Referring to Fig. 1, the shaded areas represent sectionsin a caution block where an audible signal is given between certainspeed limits. If the train enters a caution block, the engineer knowingthat he must reduce his speed until an audible signal is given properlyreduces the the speed, as a rule. As he reduces the speed in this mannerthe Warning signal finally sounds and tells him that he has now reacheda speed slightlyhigher than the minimum permissive speed setup by thehigh cam which has been shown as 4L1 miles per hour, and he is requiredto reduce his speed still a little further to, say '39 miles per hour todiscontinue sounding of the warning signal WV shown in Fig. 3.Similarly, when the medium to low cam LC is initiated the engineer isrequired to reduce his speed to, say 19 miles per hour, and in doing soan audible signal is sounded between the speed of 21 and 19 miles perhour.

The circuit for sounding the warning signal W through the top shadedareain 1 niaybe traced as follows :-beginning at the positive bus 80,wire 109, governor cam contacts 110, wires 111 and 11 2, distancecontacts 113, wires 114:, 170, 171 and 172, 58

M. P. H. contacts 173, wires 17 1 and 175, conning in non-train controlterritory) wire 177,

winding of the whistle WV, wire 178 to the negative bus 90.

When the high-to-medium cam has been initiated and the train has run theacknowledging distance of, say. 300 feet the distance contacts 180 areclosed and a circuit is completed which is closed between 39 and llmiles per hour for sounding the warning signal W which may be traced asfollows beginning at the bus 80, wire 109, governor cam contacts 110,wires 111 and 112, distance contact 113, wires 114;, 170 and 181, speedcontacts 182 closed between speeds of 89 and 411 miles per hour, Wire183, distance contacts 180, wire 18 1, distance contacts 185-186, wires187 and 175, contact finger and back contact 176 of the relay NC, wire177, winding of the whistle W, wire 178 to the negative bus 90.

As soon as the low cam is initiated by de-energization of the camstarter magnet HUS, the distance contacts 185 and 186 oper ate, therebydiscontinuing sounding of the audible signal between the speed of 39 and41 miles per hour, and closing contacts 185 and 188 which complete acircuit for the audible signal W when the speed of the train is between19 and 21 miles per hour, as follows :beginning at the positive bus 80,wire 109, governor. cam contacts 110, wires 111 and 189, governor camcontacts 110 of the medium-to-low cam, wires 191,. 115, 170, 171 and192, speed contacts 198 closed between speeds of 19 and 21 miles perhour, wire 19 1, distance contacts 188 and 185, wires 187 and 175,contact finger and back contact 176 of the non-control relay N C, wire177, winding of the whistle W, wire 178 back to the negative bus 90.

It should be noted that when the high-tomedium cam is gradually changedfrom its normal to its ultimate position the circuit referred to, whichis closed between .39 and 11 miles per hour, is broken as soon as thespeed set up by the cam governor contacts 110 is exceeded, that is,thewarning signal does not respond between these speeds when contacts110 are open; and likewise, when the mediumto-low cam is being driven toits ultimate position, no warning signal is given between 19 and 21miles per hour when the governor contacts 110 are open.

The various distances and speed referred to in connection with thewarning signal are of course only arbitrary values which have beenselected for illustrative purposes only, and it is to understood thatthe exact speed values given need not be adhered to and that the warningsignal given to inform the engineer when he has sufliciently reduced thespeed of the train upon initiation of the high-to-medium cam HC, isgiven by sounding the warning signal or whistle 7 between thespeeds of39 and 41 miles per hour, that is, just a little above and a littlebelow the minimum speed, which has been assumed to be 40 miles per hour.Instead of sounding the warning signal in a caution block between thesespeed limits only, it may be sounded whenever the speed is above thismedium speed value; and in Figs. at and 1A. has been shown anarrangement in which a warnng signal of this character is given. 7Referring to Fig. 4, the shaded area represents the various speedsthrough various sections in a caution block at which the warning signalW is sounded. It will be noted that it is sounded above 58 miles perhour the first 300 feet in the block, well as in every clear block, issounded above the speed of 39 miles per hour from this point to thepoint B (balancing resistance 7), and is sounded above the speed of 19miles per hour from the point B to the end of the block.

In Fig. 4A has been shown a car-carried circuit arrangement, similar tothat shown in Fig. 3, in which the control for the warning signal \V hasbeen modified to sound this signal in a manner as indicated by theshaded area in Fig. 41. The high and low cams HO and LC, respectively,represent similarly designated devices shown in Fig. 3, this also beingtrue of the distance cam 130, the penalty relay PR, the non-controlrelay NC, the warning signal V7, and the electro-pneumatic brake controldevice EPV; and these devices, except the warning signal W, are also controlled in the same manner as are those of Fig. 3. The apparatus shown.in this modified form of the invention is illustrated in its normalclear trailic condition, with the vehicle running at a speed somewherebetween 39 and 58 miles per hour. The brake control device EPV isenergized through a circuit which has already been traced in connectionwith the description of Fig. 3.

Operation of Fig. 4A.Let us assume that a train is running in the blockI in Fig. 1 when this block I is in a caution traflic condition becausethe block J next in advance is occupied by another train. As the trainproceeds into the block I, the high camllC is initiated for reasonsgiven in connection with the description of Fig. 3, and during thetravel of the first 300 feet, as well as when the train is moving inclear territory, a circuit is closed for sounding'the warning signal 1Vif the speed is above 58 miles per hour which may be traced as followsbeginning at the bus bar 80, wire 109, cam governor contacts 110, wires111 and 195, contacts 196 and 197 of the distance cam 198 on the low camshaft, wires 199, 200 and 201, speed contacts 202 closed above 58 milesper hour, wires 203 and 204, back contact 205 of the non-control relayNC, wire 177, warning signal 1V, wire 178 back to the other bus bar 90.1

After the train has traveled a distance of 300 feet, the distance cam130 closes its contacts 180 and completes the following circuit forsounding the audible warning signal 1V, providing the train is movingabove a speed of 39 miles per hour ;-beginning at the positive bus 80,wire 109, cam governor contacts 110, wires 111 and 195, distancecontacts 196 and 197, wires 199, 200 and 206, distance .contacts 180closed 300 feet after the high cam has been started, wire 207, speedcontacts 208 closed if the speed of the train is above 39 miles perhour, wires 209, 210 and 204, back contact 205 of the relay NC, wire177, winding of the warning signal 1V, wire 178 to the negative bus 90.7

It is thus noted that the warning signal is sounded until the trainspeed has been reduced below 39 miles per hour. When the train passesthe point B at the balancin resistance 7, the main relay MRisde-energized, thereby de-energizing the cam starter magnet of the lowcam LC and initiating movement of this cam. After the train has traveleda short distance of, say 200 feet, the distance contact 197 moves to theultimate left-hand position and closes a circuit for sounding thewarning signal W for all speeds above 19 miles per hour which may betraced as follows :beginning at the bus 80, wire 109, cam governorcontact 110 of the high cam HG, wires 111 and 189, cam governor contact110 of the low cam LC, wires 191, 211 and 199, distance contacts 197 and212, wire 213, speed contacts 214 closed above 19 miles per hour, wires215, 210, 204, back contact 205 of the relay N C, wire 177,

warning signal W, wire 178 back to the other bus 90.

By the provision of a warning signal oper ating in a manner justdescribed the engineer is continually reminded of the fact that he mustreduce his speed until the warning signal stops, so that the engineerhas had adequate information enabling him to avoid the penalty which isinflicted if he allows an automatic brake application to take place.

i lzorZ ificat'ion-s' of warning signal F 5 and 5A.Again referring tothe shaded area in Fig. 1, it should be noted that, if the train ismoving at less than 29 miles per hour when entering a caution block, nowarning signal of any kind is given. -Although it form the engineer thathe is actually below this medium speed. In Fig. 5 has beendiagrammatically illustrated by shaded area how a warning signal may besounded when the train enters a certain section, even if this 7 train istraveling at a speed lower than that enforced at the exit end of such.section, this sounding of the warning signal being accomplished byclosing an energizing circuit therefor, for a short distance of travelof the train, regardless of the speed of the train upon entering suchsection.

In the modified circuit arrangement shown in Fig. 5A, the warning signalW is not sounded at any time in a clear block, regardless of the speedat which the train is running. As the train enters a caution block,movement of a high cam HC is initiated and after a distance of, say 300feet, a circuit is closed for a short distance of travel effective atall speeds below 41 miles per hour, for sounding the warning signal 1V,this'circuit being traced as follows :beginning at the bus 80, wire 109,cam governor contacts 110, wires 111 and 195, distance contacts 216 and217, wires 218 and 219, distance contacts 180 closed after the train hastraveled a distance of 300 feet with the high cam initiated, wires 220and 221, contacts 222 closed at all speeds below 41 miles per hour, wire223, contacts 224 closed during a distance of, say 50 feet of travel ofthe train after contacts 180 have been closed, wires 225, 226 and 204,back contact 205 of the non-control relay NC, wire 177, warning signalW, wire 178 back to the negative bus 90.

Also, after the train has passed this point in its travel in a cautionblock, a circuit for sounding the warning signal W is closed between thespeeds of say 39 and 41 miles per hour, which is the same as the circuitjust traced, except that the pairs of contacts 222 and 224 are shuntedby a partial circuit as follows :--contacts 227 closed between thespeeds of 39 and 41 miles per hour and wires 228 and 229.

When the train passes the point B in a caution block, the low cam LC isinitiated, and a short distance thereafter of, say 200 feet, a circuitfor sounding the warning signal for a distance of about 50 feet, if thespeed of the train is less than 21 miles per hour, is completed and maybe traced as follows :beginning at the bus 80, wire 109,

cam governor contacts 110, wires 111 and 189, cam governor contacts 110of the low cam LC, wires 191, 230 and 218, distance contacts 217 and231, wires 232 and 233, contacts 234' closed below 21 miles per hour,wire 239, contacts 235 closed for a distance of, say 20 feet,

wires 236 and 204, back contact 205 of the non-control relay NC, wire177, warning signal Vi, wire 178 to the negative bus 90.

Another circuit, which closed for all train speeds between 19 and 21miles per hour, is completed so long as the low cam is not restored andmay be traced as follows :beginning at the bus 80, wire 109, camgovernor contacts 110, wires 111 and 189, cam governor contacts 110,wires 191, 230 and 218, distance contacts 217 and 231 controlled by thelow cam, wires 232 and 237, speed contacts 238 closed between trainspeeds of say 19 and 21 miles per hour, wires 229, 226 and 204, backcontact 205, wire 177, warning signal lV, wire 178, back to the otherbus 90.

From the foregoing description, it is noted that when a train is movinginto a caution block, an audible signal is given for a short distance atleast, providing the speed of the train is less than the minimum speedeventually enforced in the zone or section in question. In other words,in the block I illustrated, there are two sections, through the first ofwhich the high cam moves from its normal to its ultimate position, andthe second section through which the low cam is moved from its normal toits ultimate position; and a train cannot pass through either sectionwithout incurring either an automatic brake application or an audiblesignal, so that the engineer knows that if he reduces his speed untilthe audible nal is sounded and again discontinues sounding, he is notexceeding the permissive speed limits at any time.

' Modification of Fig. 5.-l'.n the application of automatic traincontrol to certain classes of railroads, it is considered expedient toleave it entirely up to the engineer as to the speed at which. the trainmay travel under clear tratlic conditions ahead. A system of thischaracter in itself may not be safe under certain conditions, becausethe speed of the train upon entering a caution block may be so highthat, even though the automatic apparatus initiates an automatic brakeapplication upon entering such block, the train would not come to a stopor a certain minimum speed before entering a danger or occupied block.It is necessary therefore, to require the train to reduce its speed to acertain restricted speed of, say 60 miles per hour, before it enters acaution block. in Fig. 6 has been illustrated a tracliway circuit forinitiating a high cam which sets up a gradually decreasing permissivespeed limit between a maximum of, say 90 miles per hour, and an ultimatespeed limit of, 60 miles per hour; and as the train enters a cautionblock, a second or low cam is initiated which gradually restricts thespeed from 60 miles per hour to a minimum of,

say 20 miles per hour. It is contemplated that a train control systemfor a maximum speed limit in a clear block of 90 miles per hourpractically leaves it up to the engineer to determine What speed thetrain shall run, unless this clear block is in the rear of a cautionblock, whereupon the train speed must be reduced to 60 miles per hourbefore entering such. a caution block. In other words, by providing anover lap control by the trackway apparatus, a sort of double blockcaution control may be setup for the car-carried apparatus. During thefirst block the train must come down to a reasonable speed of, say 60miles per hour, and through the second block its speed must be reducedfrom this speed limit to a minimum speed of 20 miles per hour.

In Fig. 6 has been shown a trackway comprising, blocks L and M andadjacent ends of blocks K and N. The various. signals, trackrelays,balancing resistance and track transformers are the same as thoseshown in Fig. l and have been assigned like reference characters withdistinctive exponents. In the arrangement shown, referring particularlyto the block L, in addition to the regular track relay at the entranceto each block a distance relay D (in block L) is controlled jointly by afront contact 24% of the track relay of the lock next in advance and the-lront contact 245 of the second block in advance, as shown. Thisdistance relay D" at a particular signal location controls the linephase current of the block next in the rear thereof, through polechanging front and back contacts 2 11 and 2 12 so that this line phaseis energized by current having one relative polarity so as to manifestclear t'aiiic conditions ahead when this relay is energized, and by thereverse relative polarity when this distancerelay D is de-enerized. Itshould, however, be noted that the line phase currenttor any particularblock is cut oil by front contact 243 of the track relay 5* (in case ofthe block L) of the block in advance so that no line phase current flowswhen the block in advance is occupied. In other words, in thearrangement shown in Fig. 6 the line phase current of one block isentirely cut off, if the block next in advance is occupied, and theinstantaneous direction of current flow in such line phase current isreversed, if the second block in advance thereof is occupied.

Although the point at which the restrictive control begins has beenillustrated as existing at the entrance to a block in Fig. 6, it shouldbe understood that the invention is not limited to this particulararrangement. For instance, the high cam, as well as the low cam, may bestarted either before or 7 after the entrance to a block by a circuitarrangement similar to that shown 1n Figs.

17A and 17B of the application of Howe and Bushnell heretofore referredto. Similarly, the trackway apparatus shown in Fig. 1 may be modified sothat the higlrto-medium cam is started either in the rear of or inadvance of a block entrance if this is found necessary to properlysafeguard the train or increase track capacity, respectively.

An automatic train control system has thus been devised in which theengineer is required to manifest his vigilance and observance of waysidesignals or cab signals, as the case may be, by operating a suitableacknowledging device in the cab, the operation of which is onlynecessary after the train has traveled a certain distance after the mainrelay has changed from a certain position to a more restrictiveposition, so that a train passing over dead sections where no trackwa-ycurrent can conveniently be applied, such as, switch frogs, staggeredjoints, crossings, cross-overs and the like will not require theengineer to operate such an acknowledging device. Further, vari-' ousarrangements have been disclosed for giving the engineer adequateinformation as to whether he has taken the necesary action to avoid anautomatic brake application, so that the engineer may avoid a penaltyassociated with such brake application by properly reducing the speed ofthe train. Also, an arrangement of trackway apparatus has been shown inwhich the speed of the train is restricted in the last clear block inthe rear of the danger block so that it is assured that an equippedtrain can only enter a caution block at a speed which assures stoppageof the train in such caution block as a result of an automatic brakeapplication upon entering such block.

Having thus shown and described several specific embodiments of theinvention, it is desired to be understood that this has been done forthe purpose of clearly disclosing the invention rather than for thepurpose of showing the scope thereof, and that various changes,additions and modifications may be made to adapt the novel train controlsystem to any one of the various types of railway systems encountered inpractice, without departing from the nature or scope of the invention orthe idea of means underlying the same.

What is desired to be secured by Letters Patent of the United Statesis 1. An automatic train control system comprising a normally energizedrelay maintained energized in response to current flowing in the trackrails ahead of the train, a normally energized brake control device,means for de-energizing said brake control device if said relay changesto indicate adverse tra-fiic conditions ahead, and manually operablemeans for preventing de-energization of said brake control device bysaid last mentioned means including a push button and means for holdingsaid push button down for a time including an electro-magnet associatedtherewith.

2. An automatic train control system comprising a normally energizedrelay maintained energized in response to current flowing in the trackrails ahead of the train, a normally energized brake control device,means for de-energizing said brake control device if said relay changesto indicate adverse trafiic conditions ahead, and manually operablemeans having an electro-magnet associated therewith which electro-magnetif energized is capable of holding said means in a depressed conditionbut is incapable of moving it into said depressed position, saidmanually operable means if operated timely preventing de-energization ofsaid brake control device by said last mentioned means.

3. Car-carried apparatus for automatic train control systems comprising,a relay instantaneously responsive to a change in traffie conditionsahead, a delayed action device delayed in accordance with the progressof the train, said device being initiated in response to de-energizationof said relay for governing the speed of the train as it proceeds alongthe trackway, means for giving an acknowledging signal by said delayedaction device andv means for automatically applying the brakes if saidacknowledging device is not operated in response to said acknowledgingsignal, and means for automatically discontinuing said acknowledgingsignal when said acknowledging device is manually operated.

4. In an automatic train control system, the combination of anelectro-responsive device on a railway vehicle adapted to assume variousdistinctive positions in accordance with trafiic conditions ahead, atapered. speed restricting means governed by said device and acting onthe usual air brake system for applying the brakes of the train if thespeed of the train is excessive, a plurality of distinctive visualsignals each of which contin uously indicates when saidelectro-responsivedevice assumes a certain position, and a distinctiveaudible signal for each of said visual signals momentarily operated whenits visual signal is energized and de-energized respectively.

5. Car-carried apparatus for automatic train control systems comprising,a permissive speed device which if initiatedsets up gradually decreasingspeed limits in accordance with the progress of the vehicle along thetrack, an actual speed device, means acting on the usual air brakesystem which applies the brakes if the actual speed eX- ceeds thepermissive speed, an audible signal sounded through a narrow band ofspeeds including the ultimate permissive speed and effective when thepermissive speed device has been initiated, whereby the engineer isadvised that he has sufficiently reduced his speed after he has passedthrough said band of speeds.

6. In a car-carried apparatus for automatic train control systems, thecombination of an electro-responsive means which is adapted to indicateclear, caution and dangcr conditions ahead of the car and which isenergized under clear tratiic conditions ahead by current flowing in atrackway circuit, two independent permissive speed devices one of whichis initiated when said electro-responsive device changes from clear tocaution and the other of which is initiated when it changes from cautionto danger, the first of said devices gradually setting up morerestrictive permissive speed limits between a maximum and a medium andthe second setting up such speed limits between a medium and a minimumspeed when initiated, an actual speed device, means for effecting anautomatic application of the brakes when the actual speed exceeds thepermissive speed, and means for giving an audible signal through twonarrow bands of actual speeds one of which includes the medium speed andthe other of which includes the minimum speed and active when therespective permissive speed devices are initiated, whereby the engineeris informed when he has sufficiently reduced his speed when changingfrom a maximum to a medium and when changing from a medium to a minimumspeed by the sounding of the audible signal for a short period of timeduring retardation of the train.

7. In an automatictrain control system; the combination of car-carriedapparatus comprising a high-to-mcdium variable permissive speed device,a medium-to-low variable permissive speed device, an actual'speeddevice, means acting on the usual air brake system and effective toapply the brakes of the train it the actual speed exceeds the lowestpermissive speed set up by said permissive speed devices,. andelectro-responsive means for controlling said permissive speed device;and of trackway means for control ling said electro-responsive deviceincluding means effective to initiate said high-to-medium permissivespeed device at the entrance to the last clear block preceding a cautionblock and for initiating said medium-to-low permissive speed device uponentering a caution block.

8. An automatic train control system according to the preceding claimwherein the high-to-medium permissive speed device varies the permissivespeed from a speed higher than the train should run under clear trafficconditions ahead to a high permissible speed value, and in which themedium-tolow permissive speed device sets up permissive speeds rangingfrom this value to a minimum speed occupied block. 7

9. Car-carried apparatus for automatic train control systems of thecontinuous inductive type comprising, a normally energized brake controldevice, a delayed action device which is adapted to be initiated fromthe trackway and which it initiated is delayed in its action inaccordance with the progress of the vehicle along the trackway, meansgoverned by said delayed action device for opening a circuit maintainingsaid device energized thereby de-energizing said brake control devicethrough a certain distance of travel only, and manually operable meanswhich it operated completes another and auxiliary circuit formaintaining said brake control device inactive.

10. Car-carried apparatus according to claim 6, further characterized bythe proconsidered safe in an vision of means for sounding an audiblesignal when the train passes a certain zone when the first permissivespeed device is initiated, and for sounding an audible signal when thetrain passes another zone when the second of said permissive speeddevices is initiated, providing the speed of the train has beensuliiciently reduced in each case, whereby the engineer is informed whenhe has sutliciently reduced the speed of the train.

11. Car-carried apparatus for automatic train control systems of thecontinuous inductive type, including, in combination with a main relaymaintained energized under favorable traffic conditions ahead by currentflowing in the track rails ahead of the train, a distance device changedin accordance with the progress of the train but normally maintainedinactive, and which if initiated will be operated to an ultimatecondition; a nor mally energized brake applying device which has itsenergizing circuit broken for a short distance of movement by saiddistance device a predetermined distance of travel of the train aftersaid distance device is initiated, and also just before said distancedevice has reached its ultimate condition; and manually operable meansfor shunting the break in said circuit.

12. Car-carried apparatus for automatic train control systems of thecontinuous in ductive type, including, in combination with a main relaymaintained energized under tavorable tratlic conditions by currentflowing in the track rails ahead of the train, a distance device changedin accordance with the progress of the train but normally maintainedinactive, and which it initiated will be operated to an ultimatecondition; a normally energized brake applying device which has itsenergizing circuit broken for a short distance of travel of the train bysaid distance device a predetermined distance of travel of the trainafter said distance device is initi-

